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* [PATCH] c++/c-common: Fix convert_vector_to_array_for_subscript for qualified vector types [PR89224]
@ 2024-02-21  3:06 Andrew Pinski
  2024-03-07  7:01 ` Andrew Pinski (QUIC)
  2024-04-30 18:53 ` Jason Merrill
  0 siblings, 2 replies; 6+ messages in thread
From: Andrew Pinski @ 2024-02-21  3:06 UTC (permalink / raw)
  To: gcc-patches; +Cc: Andrew Pinski

After r7-987-gf17a223de829cb, the access for the elements of a vector type would lose the qualifiers.
So if we had `constvector[0]`, the type of the element of the array would not have const on it.
This was due to a missing build_qualified_type for the inner type of the vector when building the array type.
We need to add back the call to build_qualified_type and now the access has the correct qualifiers. So the
overloads and even if it is a lvalue or rvalue is correctly done.

Note we correctly now reject the testcase gcc.dg/pr83415.c which was incorrectly accepted after r7-987-gf17a223de829cb.

Built and tested for aarch64-linux-gnu.

	PR c++/89224

gcc/c-family/ChangeLog:

	* c-common.cc (convert_vector_to_array_for_subscript): Call build_qualified_type
	for the inner type.

gcc/cp/ChangeLog:

	* constexpr.cc (cxx_eval_array_reference): Compare main variants
	for the vector/array types instead of the types directly.

gcc/testsuite/ChangeLog:

	* g++.dg/torture/vector-subaccess-1.C: New test.
	* gcc.dg/pr83415.c: Change warning to error.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
---
 gcc/c-family/c-common.cc                      |  7 +++++-
 gcc/cp/constexpr.cc                           |  3 ++-
 .../g++.dg/torture/vector-subaccess-1.C       | 23 +++++++++++++++++++
 gcc/testsuite/gcc.dg/pr83415.c                |  2 +-
 4 files changed, 32 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/torture/vector-subaccess-1.C

diff --git a/gcc/c-family/c-common.cc b/gcc/c-family/c-common.cc
index e15eff698df..884dd9043f9 100644
--- a/gcc/c-family/c-common.cc
+++ b/gcc/c-family/c-common.cc
@@ -8936,6 +8936,7 @@ convert_vector_to_array_for_subscript (location_t loc,
   if (gnu_vector_type_p (TREE_TYPE (*vecp)))
     {
       tree type = TREE_TYPE (*vecp);
+      tree newitype;
 
       ret = !lvalue_p (*vecp);
 
@@ -8950,8 +8951,12 @@ convert_vector_to_array_for_subscript (location_t loc,
 	 for function parameters.  */
       c_common_mark_addressable_vec (*vecp);
 
+      /* Make sure qualifiers are copied from the vector type to the new element
+	 of the array type.  */
+      newitype = build_qualified_type (TREE_TYPE (type), TYPE_QUALS (type));
+
       *vecp = build1 (VIEW_CONVERT_EXPR,
-		      build_array_type_nelts (TREE_TYPE (type),
+		      build_array_type_nelts (newitype,
 					      TYPE_VECTOR_SUBPARTS (type)),
 		      *vecp);
     }
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index fa346fe01c9..1fe91d16e8e 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -4421,7 +4421,8 @@ cxx_eval_array_reference (const constexpr_ctx *ctx, tree t,
   if (!lval
       && TREE_CODE (ary) == VIEW_CONVERT_EXPR
       && VECTOR_TYPE_P (TREE_TYPE (TREE_OPERAND (ary, 0)))
-      && TREE_TYPE (t) == TREE_TYPE (TREE_TYPE (TREE_OPERAND (ary, 0))))
+      && TYPE_MAIN_VARIANT (TREE_TYPE (t))
+	  == TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (TREE_OPERAND (ary, 0)))))
     ary = TREE_OPERAND (ary, 0);
 
   tree oldidx = TREE_OPERAND (t, 1);
diff --git a/gcc/testsuite/g++.dg/torture/vector-subaccess-1.C b/gcc/testsuite/g++.dg/torture/vector-subaccess-1.C
new file mode 100644
index 00000000000..0c8958a4e03
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/vector-subaccess-1.C
@@ -0,0 +1,23 @@
+/* PR c++/89224 */
+
+/* The access of `vector[i]` has the same qualifiers as the original
+   vector which was missing. */
+
+typedef __attribute__((vector_size(16))) unsigned char  Int8x8_t;
+
+template <class T>
+void g(T &x) {
+    __builtin_abort();
+}
+template <class T>
+void g(const T &x) {
+  __builtin_exit(0);
+}
+void f(const Int8x8_t x) {
+  g(x[0]);
+}
+int main(void)
+{
+    Int8x8_t x ={};
+    f(x);
+}
diff --git a/gcc/testsuite/gcc.dg/pr83415.c b/gcc/testsuite/gcc.dg/pr83415.c
index 5934c16d97c..2fc85031505 100644
--- a/gcc/testsuite/gcc.dg/pr83415.c
+++ b/gcc/testsuite/gcc.dg/pr83415.c
@@ -7,6 +7,6 @@ int
 main (int argc, short *argv[])
 {
   int i = argc;
-  y[i] = 7 - i; /* { dg-warning "read-only" } */
+  y[i] = 7 - i; /* { dg-error "read-only" } */
   return 0;
 }
-- 
2.43.0


^ permalink raw reply	[flat|nested] 6+ messages in thread
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2024-02-21  3:06 [PATCH] c++/c-common: Fix convert_vector_to_array_for_subscript for qualified vector types [PR89224] Andrew Pinski
2024-03-07  7:01 ` Andrew Pinski (QUIC)
2024-04-30 18:53 ` Jason Merrill
2024-04-30 19:04   ` Andrew Pinski
2024-04-30 19:12     ` Jason Merrill
2024-05-02  6:50       ` Richard Biener

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